1. Field of the Invention
The present invention relates to a black ink and color inks for ink-jet recording (hereinafter, these may be referred to as “inks for ink-jet recording”) and to an ink set for ink-jet recording.
2. Description of the Related Art
Generally, ink-jet recorded objects are required to have good water resistance, light fastness, ozone resistance and the like in order to ensure storage stability. Hence, pigment inks in which a pigment that is superior with regard to the above-listed properties compared to dyes is used as a coloring agent have attracted attention as inks for ink-jet recording.
Such pigment inks that are capable of providing recorded objects with excellent storage stability may cause a problem with respect to ejectability from an ink-jet head because the pigment used is not water soluble. Accordingly, there is a demand to improve the ejectability of such pigment inks. In addition, in order to obtain high quality text printing, there is a demand for black pigment inks that provide black-printed objects with a high optical density (OD) and clear edges. In order to obtain high quality photo images, there is a demand for color pigment inks that impart a high gloss to color-printed objects. Furthermore, ink set for ink-jet recording are similarly required to satisfy these demands.
Conventionally, the demands described above are addressed by techniques including the selection of suitable ink components such as a solvent, a dispersing agent, a pigment and the like and optimization of the average particle diameter of the pigment. By using conventional techniques, it is difficult at the present time to develop pigment inks for ink-jet recording which can provide the high quality ink-jet recorded objects demanded by the market.